1. Field of the Invention
The present invention relates to a major-minor (or parent-child) tool shank, and more particularly to a major-minor tool shank wherein the size of the automatic tool changer (hereinafter called ATC), which is installed in an automatic machine tooling center (hereinafter called MC), is reduced.
2. Prior Art
Currently, an MC requires a large number of tools in order to reduce manpower through systematization and to carry out combined production of products. Along with the increasing number of tools required, the cost related to such tools has also increased. While the tools, such as drills, taps, small mills, are small in size, the are combined into an integral unit with large tool holders having pull studs of specific dimensions.
In an attempt to streamline the foregoing product, a product which is exchangeable with small size tool holders has been developed so that conventional size tool holders can be exchanged therewith. This product is now in parctical use in some places. In this case, the conventional tool holder is called the parent (major) tool shank, and the small tool holder which is to be fitted into the parent shank is called the child (minor) shank.
However, the child taper (tapered) pot of conventional parent tool shanks has not been provided with a lock mechanism to prevent the minor tool shank from slipping off. Therefore, this type of tool shank is defective safety-wise when performing transfers during high speed exchanges.
Furthermore, the pull-studless tool holder has a specific structure that can be used only for the parent-child tool shank, and is not a generalized tool holder. Thus, there have been no major-minor tool shanks constructed combining a large size major tool shank with the foregoing pull-studless tool holder such as a minor tool shank.